In general, it is required for a metal plate used in household appliances, electrical components, timber cabinets, furniture, houseware materials, interior construction materials, etc., to have significantly excellent surface property and design property. In order to meet these requirements, various methods are used for surface machining and processing of the metal plate.
As surface machining and processing method of the metal plate used to manufacture the metal plate having excellent surface property and design property, there are two general methods well-known presently.
A first method is a method in which a vinyl chloride film is stacked onto a metal plate body coated with an adhesive, the vinyl chloride film having a transparent polyester film bonded to a surface, and a second method is a method in which a painted metal body is subjected to printing through gravure printing, followed by painting with a transparent paint.
In accordance with recent diversification of design of household appliances, the metal plate body used as an exterior material has various curved shapes, and thus, films stacked to the metal plate body are molded with various curves.
However, unlike the metal plate body, the polyester film which is a polymer causes stress with regard to deformation force that is provided at the time of a molding process, and accordingly, after the metal plate body is molded, an excitation phenomenon is generated, which causes a delamination phenomenon from the metal plate body, and thus, there is difficulty in diversifying shapes of the metal plate body.
Therefore, demand for the polyester film that is applicable to molding of a curved molded body has increased.